no moc generated , vtable link error

[eric_vi]

#include <QObject>
#include <QComboBox>
 
class testQComboBox : public  QComboBox {
 Q_OBJECT
public:
    testQComboBox(QWidget * parent = 0);
}

#include <QObject>
#include <QComboBox>

class testQComboBox : public  QComboBox {
 Q_OBJECT
public:
    testQComboBox(QWidget * parent = 0);
}

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here is my header

i am using qmake et try to subclass QComboBox to add signals.
I am getting a vtable link error because of Q_OBJECT...
i read in the doc that qmake should automatically moc the file if Q_OBJECT is in the header but it does not seem to work in my project... what am i doing wrong?

thanks for your help